Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same. More specifically, the present invention relates to a semiconductor device including a cell string with a three-dimensional structure, and a method of manufacturing the same.
Description of Related Art
Generally, a cell string of a semiconductor device is formed in a two-dimensional structure in which memory cells are formed in a single layer on a substrate. The degree of integration of the two-dimensional cell string may be improved by reducing the planar area occupied by the memory cells using a micro-pattern forming technique.
As the technology for improving the degree of integration of the two-dimensional cell string reaches its limit, a three-dimensional cell string in which memory cells are formed in a multi-layer has been suggested. The degree of integration of the three-dimensional cell string may be improved without reducing the planar area occupied by the memory cells.
The three-dimensional cell string includes interlayer insulating layers and conductive patterns, which are alternately stacked, and a through-structure passing through the interlayer insulating layers and the conductive patterns. The through-structure may include a memory layer and a channel layer. As the number of stacks of the interlayer insulating layers and the conductive patterns increases, the difficulty of forming the through-structures increases. To solve this concern, a process of forming through-structures with reduced difficulty has been proposed as follows.
The proposed process for forming through-structures includes forming a first stacked structure with portions of interlayer insulating layers and conductive patterns, forming a first part of a through-structure passing through the first stacked structure, forming a second stacked structure also having interlayer insulating layers and conductive patterns on the first stacked structure including the first part of the through-structure, and forming a second part connected to the first part of the through-structure through the second stacked structure. Likewise, when the through-structure is formed in parts divided by height, an overlay margin between the first part and the second part is insufficient, which may result in a process failure in which the second part is not connected to the first part. Additionally, when the second part of the through-structure is formed, the first stacked structure may be damaged.
As described above, there are many difficulties in performing the process of forming through-structures passing through multi-layered material layers.